Assessment of Dependent Performance Shaping Factors in SPAR-H Based on Pearson Correlation Coefficient

With the improvement of equipment reliability,human factors have become the most uncertain part in the system.The standardized Plant Analysis of Risk-Human Reliability Analysis(SPAR-H)method is a reliable method in the field of human reliability analysis(HRA)to evaluate human reliability and assess risk in large complex systems.However,the classical SPAR-H method does not consider the dependencies among performance shaping factors(PSFs),whichmay cause overestimation or underestimation of the risk of the actual situation.To address this issue,this paper proposes a new method to deal with the dependencies among PSFs in SPAR-H based on the Pearson correlation coefficient.First,the dependence between every two PSFs is measured by the Pearson correlation coefficient.Second,the weights of the PSFs are obtained by considering the total dependence degree.Finally,PSFs’multipliers are modified based on the weights of corresponding PSFs,and then used in the calculating of human error probability(HEP).A case study is used to illustrate the procedure and effectiveness of the proposed method.

Inference for accelerated bivariate dependent competing risks model based on Archimedean copulas under progressive censoring

Dependent competing risks model is a practical model in the analysis of lifetime and failure modes.The dependence can be captured using a statistical tool to explore the re-lationship among failure causes.In this paper,an Archimedean copula is chosen to describe the dependence in a constant-stress accelerated life test.We study the Archimedean copula based dependent competing risks model using parametric and nonparametric methods.The parametric likelihood inference is presented by deriving the general expression of likelihood function based on assumed survival Archimedean copula associated with the model parameter estimation.Combining the nonparametric estimation with progressive censoring and the non-parametric copula estimation,we introduce a nonparametric reliability estimation method given competing risks data.A simulation study and a real data analysis are conducted to show the performance of the estimation methods.

Multiple dependent reliability estimation of large range MEMS accelerometers in high temperature environment

In the past,only one performance parameter was considered in the reliability estimation of micro-electro-mechanical system (MEMS) accelerometers,resulting in a one-sided reliability evaluation. Aiming at the failure condition of large range MEMS accelerometers in high temperature environment,the corresponding accelerated degradation test is designed. According to the degradation condition of zero bias and scale factor,multiple dependent reliability estimation of large range MEMS accelerometers is carried out. The results show that the multiple dependent reliability estimation of the large range MEMS accelerometers can improve the accuracy of the estimation and get more accurate results.

Repair and Strengthening Assessment of Existing Bridges Based on Time-Dependent Reliability Analysis

The strategy on repair and strengthening of existing bridges based on time-dependent reliability was analyzed with the maximum expected benefit as the objective function. A sample of risk-ranking decision was illustrated based on updated inspection information with 35 survival age. The effect of improvement of live loads and difference of repair methods on time-dependent reliability of existing bridges are considered. The results show that the decision method can be used in real project, with the cost of failure consequence and the risk of failure considered.

Reliability and Availability Models of Belt Drive Systems Considering Failure Dependence

Conventional reliability models of belt drive systems in the failure mode of fatigue are mainly based on the static stress strength interference model and its extended models, which cannot consider dynamic factors in the operational duration and be used for further availability analysis. In this paper, time-dependent reliability models, failure rate models and availability models of belt drive systems are developed based on the system dynamic equations with the dynamic stress and the material property degradation taken into account. In the proposed models, dynamic failure dependence and imperfect maintenance are taken into consideration. Furthermore, the issue of time scale inconsistency between system failure rate and system availability is proposed and addressed in the proposed system availability models. Besides, Monte Carlo simulations are carried out to validate the established models. The results from the proposed models and those from the Monte Carlo simulations show a consistency. Furthermore, the case studies show that the failure dependence, imperfect maintenance and the time scale inconsistency have significant influences on system availability. The independence assumption about the belt drive systems results in underestimations of both reliability and availability. Moreover, the neglect of the time scale inconsistency causes the underestimate of the system availability. Meanwhile, these influences show obvious time-dependent characteristics.

Load Dependent Series-Parallel Systems with Common Bus Performance Sharing Mechanism

A series-parallel system was proposed with common bus performance sharing in which the performance and failure rate of the element depended on the load it was carrying. In such a system,the surplus performance of a sub-system can be transmitted to other deficient sub-systems. The transmission capacity of the common bus performance sharing mechanism is a random variable. Effects of load on element performance and failure rate were considered in this paper. A reliability evaluation algorithm based on the universal generating function technique was suggested. Numerical experiments were conducted to illustrate the algorithm.

Dynamic Fatigue Reliability Analysis of Transmission Gear Considering Failure Dependence

Multiple failuremodes and strength degradation are usually inherent in the gear transmission system,which brings new challenges for conducting fatigue reliability analysis and design.This paper proposes a novel dynamic fatigue reliability analysis method for failure dependence and strength degradation based on the combination of theCopula function and Gamma process.Firstly,the dynamic simulation model of the gear transmission system is established to obtain the dynamic stress-time history.The Gamma process is then used to describe the strength degradation to establish the dynamic stress-strength interference model.The marginal distribution functions of tooth contact fatigue and dedendumbending fatigue are calculated respectively based on the dynamic interferencemodel.Finally,the joint distribution of the two failure modes can be obtained by the t-Copula function to characterize the failure dependence,and so the dynamic fatigue reliability considering failure dependence can be estimated.The effectiveness of the proposed method is illustrated with examples.The results reveal the temporal law of reliability and the effects of failure dependence on dynamic fatigue reliability.

System reliability evaluation method considering physical dependency with FMT and BDD analytical algorithm

Recently, the physics-of-failure(PoF) method has been more and more popular in engineering to understand the failure mechanisms(FMs) of products.However, due to the lack of system modeling methods and problem-solving algorithms,the information of FMs cannot be used to evaluate system reliability.This paper presents a system reliability evaluation method with failure mechanism tree(FMT) considering physical dependency(PDEP) such as competition, trigger, acceleration, inhibition, damage accumulation, and parameter combination.And the binary decision diagram(BDD) analytical algorithm is developed to establish a system reliability model.The operation rules of ite operators for generating BDD are discussed.The flow chart of system reliability evaluation method based on FMT and BDD is proposed.The proposed method is applied in the case of an electronic controller drive unit.Results show that the method is effective to evaluate system reliability from the perspective of FM.

再生粗骨料混凝土应力-应变关系

再生粗骨料混凝土应力-应变关系是实现其材料到结构力学分析的桥梁纽带,成为再生粗骨料混凝土结构基础理论的基石。介绍了作者团队多年来在再生粗骨料混凝土应力-应变关系方面取得的研究进展:采用模型化再生粗骨料方法,研究了复杂界面过渡区对再生粗骨料混凝土破坏行为的影响,揭示了再生粗骨料混凝土细观损伤本质与演化机理;从静力作用到动力作用,系统地开展了不同工况下再生粗骨料混凝土应力-应变行为试验研究,探明了载荷条件对再生粗骨料混凝土应力与变形的影响规律并建立了相适应的力学与数学模型;进一步考虑再生粗骨料性能时空变异性,发现了再生粗骨料混凝土力学响应的概率分布特征,提出了再生粗骨料混凝土随机损伤本构关系;基于获得的本构模型,完成了再生粗骨料混凝土构件时变可靠度分析和结构动力非线性分析,为再生粗骨料混凝土在实际工程中的安全应用提供了理论支撑;提炼了相关研究结论并对未来研究工作进行了展望。

深空探测自主运行的一种可信性技术体系

未认知与不确定性是深空探测任务的基本特征.本文基于战略导向的体系化基础研究,建立了一种面向科学价值最大化的探测场景和以可靠性为核心技术基础的深空探测自主运行可信性技术体系.分析研究了深空探测场景下的可靠性概念;面向精确感知、最优计算、准确决策、快精准执行的目标要素,提出了深空探测自主运行的可信性体系框架以及“需求-认知-工程”总体技术架构;针对自主运行可信性的关键技术难点,开展了可靠性导向的多物理场、强耦合白盒建模,复杂网络故障传播机制分析,COTS元器件深空探测应用的高可靠保证,以及“模型+数据+知识”一体的融合机制分析等研究.对该技术体系的关键技术验证策略及其最小系统在卫星星座中的应用进行了验证,结果表明,所提出的技术体系具有较高的工程价值.

考虑抗力非平稳劣化和荷载相关性的桥梁可靠性分析

桥梁结构在服役期间受到环境侵蚀和均值增大的相关荷载作用,承载力降低,安全状况不容乐观。为了准确评估服役桥梁在剩余使用寿命内的安全性能,需要考虑结构抗力劣化的非平稳特性以及荷载的时间相关性。该文基于时变可靠度理论,采用Gamma分布描述结构抗力的非平稳劣化过程,并用二维联合分布函数表示相邻荷载的相关性,基于贝叶斯原理,提出了计算公式,并采用蒙特卡洛模拟(MCS)对计算结果进行了验证。对四川省某钢筋混凝土简支梁桥的时变可靠度分析结果表明:在单次条件概率分子的二重积分结果大于0.7时,公式计算结果与MCS结果接近,证明了其正确性;Gamma劣化过程的尺度参数越大,荷载的时间相关性越弱,结构失效概率越大;当作用于结构的车辆荷载年均增长率超过2%时,桥梁在30年内失效的概率较大,需要对结构进行定期监测、养护和维修。

手机依赖高风险人群筛查量表的编制及性能测试

目的:编制中文简短手机依赖问卷(SPDQ),为手机依赖的群体筛查和公共卫生人群监测提供工具。方法:采用同组研究设计获得221名大学生4次测量数据。内部一致性信度(Cronbach′α)和重测信度(ICC)系数分析问卷信度,探索性和验证性因子分析确定问卷效度,ROC分析确定判断手机依赖的临界值。结果:SPDQ由7个条目构成,具有较高的内部一致性、重测信度与良好的结构效度和效标效度。问卷包含两因子模型,包括认知/心理依赖和行为依赖。验证性因子分析设定所有题目为依赖表现,4次测量χ^(2)值分别为15.23,11.54,13.60和14.11,P均大于0.05。以简短智能手机依赖指数量表(SPAI-SF)为金标准,确定4/5为SPDQ筛查分界值。结论:本研究编制的SPDQ符合心理测量学标准,可作为手机依赖潜在风险人群的筛查工具。

空间辐射环境下SiC功率MOSFET栅氧长期可靠性研究

利用等效1 MeV中子和γ射线对1200 V SiC功率MOSFET进行辐射,研究了电离损伤和位移损伤对器件的影响,并分析了辐射后器件栅氧长期可靠性。结果表明:中子辐射后器件导通电阻发生明显退化,与辐射引入近界面缺陷降低载流子寿命和载流子迁移率有关。时间依赖的介质击穿(TDDB)结果表明,栅泄漏电流呈现先增加后降低趋势,与空穴捕获和电子捕获效应有关。中子辐射后栅漏电演化形式未改变,但氧化层击穿时间增加,这是中子辐射缺陷增加了Fowler-Nordheim(FN)隧穿势垒的缘故。总剂量辐射在器件氧化层内引入陷阱电荷,使得器件阈值电压负向漂移。随后的TDDB测试表明,与中子辐射一致,总剂量辐射未改变栅漏电演化形式,但氧化层击穿时间提前。这是总剂量辐射在氧化层内引入额外空穴陷阱和中性电子陷阱的缘故。

基于混凝土碳化与有限元的渡槽时变可靠度分析

提出一种基于有限元的渡槽碳化时变可靠度分析方法。首先,利用Midas Civil软件建立钢筋混凝土渡槽的三维有限元模型,结合混凝土碳化深度预测模型构建渡槽时变功能函数。接着,将点估计法与结构有限元分析相结合,求解考虑混凝土碳化功能函数随机变量的前4阶矩。然后,通过双幂变换和JarqueBera检验,将原有功能函数转化为近似正态分布,采用高阶无迹变换(HUT)估计转化后功能函数的前4阶矩,进而计算混凝土碳化的渡槽时变可靠指标。最后,将计算所得时变可靠指标结果与4阶矩法和Monte Carlo模拟(MCS)结果进行比较分析。研究结果表明:本文提出的方法能够有效解决4阶矩法在高可靠指标计算时误差较大的问题,并且与MCS结果相比,本文所提方法具有效率高、精度高等特点。

耦合级联失效系统可靠性建模与分析

现实生活中绝大多数系统并不是孤立存在的,如通信网和电网,它们相互依存、相互影响,这种系统间的耦合关系使得级联失效范围变得更广,导致级联过程更为复杂,从而影响整个系统可靠性及其正常运行。针对此问题,论文以电力通信系统为研究背景,给出了耦合系统转移率的解析表达,分析了元件负载增加影响元件故障率的级联失效效应和子系统间的相依关系,建立了耦合级联失效系统的可靠性模型,并证明了系统可靠度的计算方法和解析式结果。并且利用一个算例展示了耦合系统发生级联失效的具体过程,以验证该方法的有效性与可行性。本文为基于负载和时间的耦合系统的级联研究提供了新的思路,可拓展至不同的耦合关系、耦合强度以及不同的负载分配模式来进一步研究系统的级联失效过程以及可靠度分析。

结合BP神经网络和高阶矩法的渡槽侧墙抗弯时变可靠度分析

基于BP神经网络与高阶矩法,结合实测数据,提出了钢筋混凝土渡槽侧墙抗弯时变可靠度分析方法。为评估钢筋锈蚀影响下的渡槽侧墙抗弯时变可靠度,考虑混凝土结构中钢筋有效截面面积损失效应,导出渡槽侧墙承载能力极限状态下的抗弯时变功能函数;接着,结合钢筋锈蚀实测数据和BP神经网络原理设计钢筋锈蚀速率预测模型,通过半球形点蚀模型建立混凝土结构中钢筋有效截面面积计算公式;在此基础上,引入点估计-高阶矩可靠度理论发展渡槽结构时变可靠度分析方法,最后将提出的方法应用于某实际渡槽侧墙抗弯时变可靠度分析。结果表明:较之以往的8个实用经验模型,本文所建BP神经网络预测模型可以更准确、综合、简便、快速地预测混凝土结构中的钢筋锈蚀速率;通过与蒙特卡洛模拟法对比验证,本文方法求解时变可靠指标高效准确,可为渡槽时变可靠度评估预测提供一条有效的途径。

An Improved CREAM Model Based on DS Evidence Theory and DEMATEL

Cognitive Reliability and Error Analysis Method(CREAM)is widely used in human reliability analysis(HRA).It defines nine common performance conditions(CPCs),which represent the factors thatmay affect human reliability and are used to modify the cognitive failure probability(CFP).However,the levels of CPCs are usually determined by domain experts,whichmay be subjective and uncertain.What’smore,the classicCREAMassumes that the CPCs are independent,which is unrealistic.Ignoring the dependence among CPCs will result in repeated calculations of the influence of the CPCs on CFP and lead to unreasonable reliability evaluation.To address the issue of uncertain information modeling and processing,this paper introduces evidence theory to evaluate the CPC levels in specific scenarios.To address the issue of dependence modeling,the Decision-Making Trial and Evaluation Laboratory(DEMATEL)method is used to process the dependence among CPCs and calculate the relative weights of each CPC,thus modifying the multiplier of the CPCs.The detailed process of the proposed method is illustrated in this paper and the CFP estimated by the proposed method is more reasonable.

基于PDEM的正交异性钢桥面板焊接节点时变疲劳可靠度评估

提出了基于概率密度演化方法的正交异性钢桥面板焊接节点时变疲劳可靠度评估方法,并以润扬大桥顶板-U肋焊接节点为对象开展应用研究。首先,基于S-N曲线和Miner准则,构建了可同时考虑疲劳性能退化和荷载效应增长的钢桥面板焊接节点疲劳极限状态函数,并导出其概率密度演化方程。然后,采用有限差分法求解该方程,据此得到概率密度演化曲面,进而建立其时变疲劳可靠度评估方法。最后,通过工程实例验证了所提方法的可行性和准确性,并探讨了疲劳性能退化和荷载效应增长对该节点时变疲劳可靠度的影响规律。研究表明:与Monte Carlo法相比,该方法不仅精确高效,还能捕捉概率密度演化信息;疲劳性能退化和荷载效应增长会显著影响钢桥面板焊接节点的疲劳寿命。

考虑抗力退化的混凝土坝时变可靠性分析方法

混凝土坝服役期间,由于具有随机时变性,结构抗力性能随时间发生不确定性退化,因此有必要从时变可靠度角度评估其运行安全性能。在概率密度演化理论(PDEM)的框架内,提出一种基于PDEM的时变可靠性分析方法(EP-TSR),即利用演化过程建立坝体结构时变响应的概率密度演化方程,引进虚拟随机过程技术再次建立概率密度演化方程并求解得到随机性初始条件,最终得到坝体静态响应的概率密度曲线演化规律和丰富的时变概率统计信息,并将该方法与Monte Carlo方法计算得到的结果进行对比。结果表明,EP-TSR法应用于混凝土坝有效、合理,且具有更高的计算精度和效率。

既有结构鉴定理论与技术的发展趋势研究

通过回顾国内外工程建设的发展历程,探讨了既有结构鉴定存在的问题以及鉴定工作的重要性和紧迫性。对比分析了国内外鉴定规范的发展和国内鉴定标准之间的关系。最后介绍了现有3种鉴定方法及其优缺点,并归纳总结了概率鉴定法的研究进展,得出了同时考虑抗力退化和荷载变化的既有结构时变可靠度鉴定方法是未来的发展趋势。